Friction draft gear



Oct. 29, 1957 Filed Jan. 19, 1954 W. E. GRAY FRICTION DRAFT GEAR 2Sheets-Sheet 1 /7 ODA/E YS.

Oct. 29, 1957 w. E. GRAY 2,811,264

FRICTION DRAFT GEAR Filed Jan. 19. 1954 2 Sheets-Sheet 2 if P/VEYS.

nite States FRICTION DRAFT GEAR William E. Gray, West Lafayette, Ind.

Application January 19, 1954, Serial No. 404,989

8 Claims. (Cl. 213-45) This invention relates to draft gears, and moreparticularly to draft gears in which the cushioning element is a blockor a series of blocks of rubber or similar compressible material.

Among the objects of the invention are to produce an improved draft gearwhich can be sirnply and economically manufactured and which, inservice, will prove durable and effective to accomplish its intendedpurpose; to prevent damage to the rubber cushioning material orinterference by that material in the proper functioning of the gear; andto improve the releasing operation of the gear.

In carrying out the invention in its preferred form, I provide anelongated, cylindrical hollow sleeve or housing, preferably of ovalcross section; and within such housing, at each end thereof, I provide apair of laterally separable shoes adapted to bear frictionally againstthe inner surface of the housing when the gear is collapsed under draftor bufng loads to move the shoes longitudinally of the housing. Theopposed faces of the shoes of each pair are recessed to provide for thereception of blocks of rubber or similar elastically compressiblematerial which oppose movement of either pair of shoes toward the otherand which, when compressed longitudinally as the result of draft orbufling loads, expand transversely to force the shoes outwardly againstthe housing. To prevent the rubber blocks from becoming pinched betweenthe shoes, they are surrounded by sheet-metal liners bridging the gapbetween the shoes. Desirably, the housing-engaging surfaces of the shoesare not complementary to the inner surface of the housing but insteadare so shaped as to engage the housing only at and near their midpoints;and the housing is elastically distortable so that when the shoes areforced apart as a result of draft or bufng loads, the housing will bedistorted to increase the area of contact between its inner surface andthe shoes. This feature facilitates release of the gear and tends toprevent it from becoming locked in closed condition. The accompanyingdrawings illustrate the invention:

Fig. l is a longitudinal, horizontal section through a draft gear inopen condition;

Fig. 2 is a transverse vertical section on the line 2 2 of Fig. l;

Fig. 3 is a view similar to Fig. l, but illustrating the gear in closedcondition; and

Fig. 4 is a View similar to Fig. 2 but showing the condition existingwhen the gear is closed.

The draft gear is shown inthe drawings as carried from draft orcenter-sills of a car frame and between front and rear stop lugs 11 and12. In a manner yet to be described, the gear is adapted to cushion bothcar-pushing and car-pulling shocks transmitted by the car-pushingdraw-bar 13, or by the car-pulling yoke 14, through the draft gear tothe car frame. A front follower block 16 located in rear of the lugs 11engages the adjacent ends of a front pair of friction shoes 17; while arear follower block 18 lying in front of the rear stop lugs 12 engagesthe rear ends of a pair of rear shoes 19. The shoes 17 and i9 arelocated within a housing 21 against the inner 2,811,264 Patented Oct.29, 1957 ice surface of which the shoes of each pair are forced uponclosing of the gear.

The two shoes of each pair are provided in their opposed faces withrecesses cooperating to provide a generally cylindrical cavity withinwhich are located blocks 23 of rubber or similar elasticailycompressible material. As shown, there are an inner and an outercompressible block Z3 located within the cavity defined by each pair ofshoes, such two blocks being separated by a rigid inter mediate spacer28. The shoes are provided at their outer ends with flanges 25 whichextend toward each other across the end of the block-receiving cavity;and between each pair of such flanges and the adjacent outer block 23there is interposed an end spacer 26.

In the open position of the gear, rshown in Fig. l, the two pairs ofshoes project outwardly beyond the ends of the housing 21 intoengagement with the follower blocks 16 and 18; and at their inner endsthe two pairs of shoes are spaced apart to permit them to move towardeach other as an incident to closing of the gear. A rigid filler block24, dimensioned to enter the cavities containing the blocks 23, isinterposed between the inner ones of such blocks. The extent of theblock 24 longitudinally of the gear is such that with the gear fullyopen the block 24 projects into each cavity for a short distance.

When the gear is called upon to cushion a butiing jolt transmittedthrough it from the draw bar 13 to the rear stop lugs 12, the rearwardmovement of the draw bar 13 forces the front follower block rearwardly.Since rearward movement of the rear follower block is prevented by itsengagement with stop lugs 12, the two pairs of shoes 17 and 19 will beforced toward each other and the rubber blocks 23 will becompressedlongitudinally and expanded laterally, the latter actionforcing the two shoes of each pair outwardly away from each other andinto hrm frictional engagement with the inner surface of the housing 21.Collapse or closing of the gear will thus be opposed both by theresilient resistance of the rubber blocks and by friction between theshoes and the housing; and both those components will increase asclosing proceeds toward its limit. Under a draft or pulling shock, theaction is essentially the same, the only difference being that the rearfollower block 18 moves forwardly While the front follower block is heldagainst forward movement by the front stop lugs 11.

When closing of the gear has been completed, its subsequent opening orextension is effected as a result of longitudinal forces exerted by thecompressed blocks 23 upon the shoe-anges 25; and as the compressedblocks are forcing the shoes outwardly against the housing, frictionbetween the housing and the shoes will oppose opening of the gear. lockin closed condition as arresult of such friction I prefer to shape thehousing 21 and the shoes in such a manner that their interengaging facesare not exactly complementary with each other. As indicated in Fig. 2,the housing is preferably generally oval in cross-section, and the shoesof each pair are arranged to move toward and away from each other alongthe major axis of the oval. The shoes are so shaped that when the gearis open they engage the `housing only 'at 'points near their center, oradjacent the ends of the major housing-axis. In other words, the sidesurfaces of the shoes are relieved t0 provide clearance such as isindicated atv 32 in Fig. 2.

The housing possesses sufficient elastic distortability to permit it tocollapse vertically, or in the direction of its minor axis, when theshoes are forced apart toexpand the housing horizontally or along itsmajor axis. Such reduction in the minor axis of the housing increasesthe area of contact between it and the shoes, bytaking up the clearance32. As a result of the arrangement just described, the tendency of thegear to lock closed To reduce the tendency of the gear toV position ismaterially reduced, as more fully set forth and described in myco-pendingV application Serial No. 295,718', led June 26, 1952.

To eliminate the possibility that any portion of the rubber blocks willbe pinched between the shoes upon closing of the gear, the blocks aredesirably surrounded with sheet-metal liners bridging the gaps at whichany suchl pinching might occur. As shown,l one such liner is associatedwith each pair of shoes, the liner comprising two pieces of sheet-metaleach bent into an arcuate crosssection of somewhat more than 180 extentso that when inplace their edge portions will overlap, as indicated at33- in Fig. 2. Adjacent the end spacer 26, portions of each liner arebent inwardly to provide tlanges or tongues 35 overlying the outer endof the adjacent block 21% to locateI the linerY axially of theassociated. shoes and to prevent entry of the compressible material intothe spaces between the shoes and the spacer 26 when the gear is closed.At its opposite end, each liner laps the ller 24, but does not extendthereover far enough to engageV the adjacent end of the opposite` linervupon closing of the gear.

The housing 21 is not anchored to` the sills 10, but is free to floatlongitudinally as limitedy by its possibilities of engagement with thefollower blocks 16v and 18. To insure that the housing is centeredlongitudinally with respect to the shoes when the gear isV open, atleast one of the shoes 17 and one of the shoes 19 is provided in itsouter surface with a groove 37' which extends inwardly of theV shoe to apoint within the housing 21, and the housing 21 is provided with pins 38received in such grooves. The arrangement is such that when the gear isopen the pins-38 lie at the inner ends of the grooves 37, thus locatingthe housing in denite, centered position, with respect to the shoes andpreventing one pair of' shoes from projecting outwardly beyond thehousing when the gear is in the open (Fig. l) condition, the.

grooves 37 and pins 38 perform the additionalfunction of holding theoverall length ofthe shoes-and-housing assembl-yto a predeterminednmaximum suchas to facilitate its positioning between the follower blocks16 and 18.

As indicated, the rubber blocksV 23 are provided with holes 40 extendingthrough them longitudinally of the gear.- Aswill be obvious, the numberand cross-sectional area of such holes will determine' thel lateralpressure exerted by each block when compressed longitudinally to anygiven extent. Holes 40, which taper toward their longitudinal centers,as shown in- Fig. 1, are preferred, as such holes tend to assume acylindrical form (Fig. 2) when the blocks 23' are-compressed' upon.closing of the gear.

I claim as rnyinvention:A Y

1. Ina draft gear having a longitudinally extended housing and a pair ofopposed" shoes longitudinally movable in said housing, means operable inresponse to draft or buing forces formoving said shoes longitudinallyin-said housing, and a massY of compressible, resilient material foropposing such longitudinall movement of said shoes, said mass beingvconfined between. said shoes whereby when compressed longitudinally itvwill expand laterallyto urge said shoes apart and: into rm frictional'-contact wit-h the innerA surfaceY of' the housing, said housing beingcircumferentially continuous and' elastically distortable, said shoesrespectivelyhavingcentralportions engaging said housing at adjacentopposite ends; of a diameter thereof, whereby outwardLv pressure.exerted on the-` housing by the central portions of the shoes will.enlargei the housinginthe'` direction of suchdiameter and: contractI itthe-perpendicu1ar direction,

. 4 said shoes having side portions spaced from the housing when thelatter is undistorted but engageable by the housing when it contracts insuch perpendicular direction.

2. A draft gear as set forth in claim 1 in which the housing is ofgenerally oval cross-section, the shoes being disposed within thehousing in such positions that their respective center portions engagethe housing at and adjacent the ends of its major diameter.

3. The invention of claim 1 with.' the addition that there are two pairsof said shoes locatedl respectively at opposite ends of the housing andmovable toward each other under draft or buthng forces, the two shoes ofeach pair being provided with opposed recesses defining a cavity, saidmass of compressible material including two blocks located respectivelyin said cavities, and a rigid filler block disposed between the blocksof compressible material and extending into both said cavities.

4. The invention of claim 1 with the addition that the opposed faces of`said shoes are recessed to provide a cavity for the reception of saidmass of compressible material, and a sheet-metal liner disposed betweensaid mass and said shoes, said liner overlapping both said shoesperipherally of said mass of compressible material and extendinglongitudinally of the shoes for the length thereof.

5. The invention of claim 1 with the addition that the opposed faces ofsaid shoes are recessed to provide a cavity for the reception of. saidmass of compressible material', and a sheet-metal liner surrounding saidmass andv extending longitudinally of the draft gear for the length ofsaid mass.

6. In a draft gear havinga longitudinally extended housing and a pair ofopposed. shoes longitudinally movable in said4 housing, means operablein response to draft or buing forces for moving said shoes rearwardly insaid housing, the opposed. faces of said shoes being recessed to providea cavity, ablock of resilient compressible material located in andconfined by said cavity for opposing rearward movement of the shoesinthe housing whereby said block, when compressed longitudinally, willexpand laterally to urge the shoes apart into hrm frictionalengagementwith the housing, and a sheet-metal liner disposed betweensaid block and shoes.

7l In aY draft gear having a longitudinally extended housingI and a pairof opposed shoes longitudinallyv movable in said housing, means operablein response to draft or huling forces for moving said shoes rearwardlyin said housing; ther opposed faces of said shoes being recessed. toprovidev a cavity, a block of4 resilient com-A pressibleY materiallocated in and confined by said cavity for opposing rearward. movementof the shoes. in the housing whereby said block, when compressedlongitudihally,. will. expand laterally to' urge the shoes apart. intofirm frictional engagement with thehousing, and a sheetmetal linersurroundingl saidv mass.

8. The invention of claim 6'with the addition that said shoes areprovided at their outer ends with flanges dening a bottom for saidcavity, said liner having an inbent tlange conned between said block andat least one of saidshoe-anges.

References` Cited in the le` of this patent- UNTTEDv STATES PATENTS-1,200,642 OConnor Oct. 10, 1916 1,512,926 Haseltine Oct. 28, 19242,222,479 Cottrell Nov. 19, 1940 2,328,877 Gallagher Sept. 7, 19432,328,878 Gallagher Sept. 7, 1943 2,417,410 Gray Mar. 18, 1947 2,745,560Gray May 15, 1956y

